Apex seal for rotary piston engine

ABSTRACT

An apex seal for rotary piston engine has the main body of the apex seal made of a light metal selected from the group of aluminum, aluminum alloy, magnesium, and magnesium alloy with an oxidized layer of more than 10 microns in thickness formed by anodic treatment on at least the sliding surface of the main body, and a heat resistant resin impregnating the oxidized layer.

Sept. 4, 1973 el], Mion,Zinn & McPeak 3,554,677 l/l97l Zapf et al. Primary Examiner-Samuel B. Rothberg A q" !l"mi2 r:@nl.- Smith Attorney Sughrue, Rothw et al.

[57] 7 ABSTRACT An apex seal for rotary piston engine has the main body of the apex seal made of a light metal selected from the group of aluminum, aluminum alloy, magnesium, and magnesium alloy with an oxidized layer of more than 10 microns in thickness fonned by anodic treatment on at least the sliding surface of the main body, and a heat resistant resinimpregnating the oxidized layer.

2 Claims, 6 Drawing Figures F0lc 19/02 418/113,120,122, 418/123, 124, 178, 179; 277/235, 235 A lliroshi Sakamakl, Utsunomiya, Japan Assignee: Nippon Piston Ring Co., Ltd., Tokyo,

Japan Oct. 21, 1971 Appl. No.: 191,287

Foreign Application Priority Data Oct. 24, I970 Japan..........................

References Cited UNITED STATES PATENTS 9/1971 Winston..............................

United States Patent Sakamaki APEX SEAL FOR ROTARY PISTON ENGINE [75] lnventor:

[22] Filed:

[58] Field of Search...................

PAIENIEM 3.756.754

' sum 1 m2 FIG. I

Pmemmw' SHEET 2 BF 2 FIG. 4

1 APEX SEAL FOR ROTARY PISTON ENGINE BACKGROUND OF THE INVENTION 1. FIELD OF THE INVENTION This invention relates to an apex seal employed between the rotor and the center housing of a rotary engine.

2. DESCRIPTION OF THE PRIOR ART Apex seals are mounted on the apex portions of the V rotor for ensuring fluid-tightness while the rotor rotates inside the center housing of a multi-circular configuration with the apex seal contacting the inner surface of the center housing. For assuring the fluid-tightness of the apex seal to a satifac tory extent, provisions are made so that the apex seal is heavily depressed onto the inner surface of the center housing not only by a number of springs provided between the rear side of the apex seal and the apex portion of the rotor, but also by the centrifugal force caused by the mass of the apex seal, gas pressure caused by the operational fluid, and

the like.

However, because of the excessive depressing force for the apex seal, wear of the apex seal and the inner surface of the center housing is found to .betoo high,

and furthermore, there is a tendency to cause irregular 1 wear on the inner surface of the center housing. Although various reasons cause the irregular wear, the most important is due to the mass of the apex seal.

To be more specific, the frictional force due tothe centrifugal force caused by the rotation of the rotor, which appears between the apex seal and the inner surface of the center housing, is increased in proportion to as in the wear resistivity, and an apex seal satisfying all of these requirements is yet tobe found.

SUMMARY OF THE INVENTION Therefore, the primary object of the present invention is to provide an apex seal which can satisfy all of the above described requirements.

This and other objects of the present invention can be achieved by an improved construction of the apex seal which comprises a main apex seal body made. ofa

FIG. 1 is a vertical sectional view of a rotary piston engine equipped with the apex seal according to the present invention;

FIG. 2 is a perspective view of an apex seal constituting an embodiment of the present invention;

FIG. 3 is a longitudinalsectional view taken along the line III-III in FIG. 2;

FIG. 4 is a longitudinal sectional view similar to FIG. 3 of another embodiment of the present invention;

FIG. 5 is a plan view of still another embodiment of the invention; and

FIG. 6 is a longitudinal sectional view of an apex seal which constitutes still another embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION Referring now to FIG. 1, there is indicated a rotary engine comprising a center housing 1 having an internal surface in the form of a multi-circular configuration, side housings 2, 2, a rotor 3 which rotates eccentrically within the center housing 1, a groove 4 providecl in each apex portion of the rotor 3 projected adjacent to the internal surface of the center housing 1, an apex seal 5 insertedin the groove 4 so that the seal 5 can be freelymoved inside of the groove 4, and a number of springs 6 provided on the rear side of the apex seal 5' for urging the slidable surfaceSl of the apex seal 5 onto the internal surface 1' of the center housing 1.

As best seen in FIGS. 2 and 3, theapexseal 5 is made of aluminum, aluminum alloy, magnesium, ormagnesium alloy, so that the mass of the apex seal is much reduced despite its high mechanical strength.

However, the apex seal made of aluminum, magnesium, or their alloys has a shortcoming of inferior wear resistivity, and for overcoming the shortcoming, an oxidized layer 7 is formed over the sliding "surface 51 of Q the apex seal 5, which otherwise may be easily worn out, and also on the side surface 52", 52 of the apex seal throughan anodic treatment. The thickness of theoxidized layer 7. is selected tobe more than 10 microns.

material selected from a group consisting of aluminum,

BRIEF DESCRIPTION OF THE DRAWINGS In the drawing:

For further imparting wearv resistivity and selflubricatingnature, the oxidized layer 7 is impregnated bya heat resistant resin suchas fluoric resin or silicone resin. t

Alternatively, the sliding surface Sland the end surfaces'52, 52may be provided-with a number of grooves 9 as shown in FIG. 4, and a wear resistant material 10 such as iron nitride'or tungsten may fill the grooves' 9. In this case, the shape, orientation, and the number of the grooves 9 may be selected to adapt the type and operation of the rotary engine. Forinstance, rectilinear grooves 9 may be cut along the length of the apex seal as shown in FIG. 5,.and a wear resistant material 10' which/is similar to the material 10 may fill the inside- 0f the grooves. I I Otherwise, the sliding surface SI and the end surfaces 52, 52 of the apex seal may be provided with an heat resistant synthetic resin 8, and a, number of oxidized layer 7 of more than 10 microns in thickness, the oxidized layer 7 being further impregnated with a I grooves 9 may then be provided at least on thesliding surface 51 of the apex seal asjshown in FIG/6. In these grooves-9, a wear resistant material 10 similar to those employed in FIGS. 4and 5 is placed. In this example,

superior wear resistivity can be obtained due to the multiplying effects of the oxidized layer 7, wear resistant synthetic resin 8, and the wear resistant material 10.

As described hereinbefore, the mass of the apex seal of this invention is very small as it is made of aluminum, magnesium, or their alloys, and the mechanical strength thereof is also very high. Furthermore, on the easily wearable sliding surface and the end surfaces of the apex seal, an oxidized layer is formed by way of anodic treatment, which is thereafter impregnated by a heat resistant resin. For this reason, the resultant apex seal is ensured to have superior wear resistivity, selflubricating nature, and initial affinity.

What is claimed is:

1. An apex seal for a rotary engine comprising:

an apex seal main body made of a light metal selected from the group consisting of aluminum, aluminum alloy, magnesium, and magnesium alloy,

an oxidized layer of more than l0 microns in thick ness formed by anodic treatment on at least the sliding surface of the main body, and

a heat resistant resin impregnating the oxidized layer.

2. An apex seal for a rotary engine comprising:

an apex seal main body made of a light metal selected from the group consisting of aluminum, aluminum alloy, magnesium, and magnesium alloy,

an oxidized layer of more than 10 microns in thickness formed by anodic treatment on at least the sliding surface of the main body,

a heat resistant resin impregnating the oxidized layer,

a number of grooves providedat least on the sliding surface of the main body, and

t 1 i i i 

2. An apex seal for a rotary engine comprising: an apex seal main body made of a light metal selected from the group consisting of aluminum, aluminum alloy, magnesium, and magnesium alloy, an oxidized layer of more than 10 microns in thickness formed by anodic treatment on at least the sliding surface of the main body, a heat resistant resin impregnating the oxidized layer, a number of grooves provided at least on the sliding surface of the main body, and a wear resistant material filling said grooves. 